"There are a lot of balls in the air right now with the pitching staff," the manager said after Sunday's 9-8 loss, the Reds' third defeat in a row. "If we're going to be competitive, we have to get a lot out of our pitching staff. Who the 12 are going to be is up in the air."
Cincinnati starters allowed 21 runs in 11 innings during the last three games of the series, a 17.18 ERA.
Price tried to shake up his office, dropping Billy Hamilton from leadoff to eighth in the batting order and Jay Bruce from fifth to seventh. Hamilton went 1 for 3, raising his average to .214. Bruce was 3 for 5, upping his average to .190.
Hamilton didn't start in the leadoff slot for the first time since his first major league start on Sept. 18, 2013. He had made 171 consecutive starts at leadoff before hitting eighth Sunday.
"We've asked a lot out of Billy coming from Triple A," Price said. "He is motivated but he's still figuring out some things."
Reds are 0 for 18 with three walks.
Brandon Belt homered for the third time in three games, Nori Aoki drove in three runs and the Giants won after nearly wasting a 6-1 lead.
"I'm seeing the ball well," said Belt, who drove in seven runs as the Giants won three straight after losing the series opener. "I had a couple of games where I had some hiccups, but I'm getting back to what I do best — seeing the ball."
Hunter Pence homered in his second game back from a broken forearm. The World Series champions won three straight games in Cincinnati for the first time since 2005 and at 20-18 moved two games over .500 for the first time since they were 3-1. The Giants had 16 hits, matching their season high, and outscored opponents 44-21 on a six-game trip.
"That's what happens when you've got four or five guys swinging the bat well," Giants manager Bruce Bochy said. "This is a little bit more like who we are. We're going to be more consistent than we were early in the season."
Cincinnati closed within a run in the third after their first six batters reached against Chris Heston. Marlon Byrd's RBI single, Brandon Phillips' bases-loaded hit-by-pitch and Bruce's run-scoring single made it 6-4.
Bruce's line drive hit the base of the right-field fence.
"When I hit it I thought it was going out of the park," he said. "The cross wind knocked it down."
After Phillips' second home run this season cut Cincinnati's deficit to 7-6 in the fifth, Hamilton hit a two-out single and pinch-hitter Skip Schumaker's double bounced into the stands — preventing Hamilton from scoring.
"In a game like that, it's always the little things," Price said. "There were plays we could have made."
Petit allowed one run and three hits in three innings, Sergio Romo struck out Todd Frazier with the potential tying run on third to end the eighth and Santiago Casilla struck out the side in the ninth on nine pitches for his ninth save in 11 chances.
Giants: Bochy said center fielder Angel Pagan could have started, but Bochy chose to give him the day off. Pagan left Saturday's game with back spasms.
Reds: LHP Manny Parra, on the disabled list since April 29 with a strained neck, developed elbow tenderness after pitching off a mound on Friday, manager Bryan Price said. Parra will need one or two bullpen session and a rehabilitation stint in the minors before his return.
Giants: San Francisco opens a three-day homestand on Tuesday against the Los Angeles Dodgers, then has a seven-game trip.
Reds: Cincinnati opens a two-game interleague series at Kansas City on Tuesday. RHP Johnny Cueto allowed five runs — none earned ... in seven innings of a 7-1 Reds' loss at Kansas City on June 14, 2009.
Pence went 2 for 5 to improve to .426 (23 for 54) with six extra-base hits in his last 13 games against Cincinnati.